- NEW: Dr. Drew Pinsky: Autopsy report suggests seizure possibly from drug, alcohol withdrawal
- Coroner: Death was from accidental drowning; cocaine, heart disease were factors
- Investigators found "a small spoon with a white crystal like substance " in her bathroom
- Her assistant found Houston 35 minutes after telling her to take a bath
Los Angeles (CNN) -- Whitney Houston drowned face down in a tub of "extremely hot water" about 12 inches deep, the final autopsy report on the singer's death said.
The Los Angeles County coroner ruled that Houston's February 11 death was an accidental drowning with the "effects of atherosclerotic heart disease and cocaine use" as contributing factors.
The coroner's report stopped short of detailing what happened to Houston, but HLN's Dr. Drew Pinsky, an addiction medicine specialist, examined the autopsy report for CNN and suggested she might have suffered a seizure brought on by the use of cocaine possibly combined with a withdrawal from alcohol and a prescription sedative.
An empty bottle of the Xanax was found in her room, but the level of the sedative found in her blood was low, he said. Empty beer bottles were also found, but alcohol was not detected in her body, he said.
"To me, a sudden drop off in the Xanax level, a drop off in your alcohol consumption, add cocaine, that's a recipe for a seizure," Pinsky said. "Somebody who's now upside down in a bathtub could easily seize and drown."
The coroner's report note that Houston suffered several small scald burns on her face at the time of her death.
A 60% narrowing of her arteries found in the autopsy is "very mild heart disease," Pinsky said, which should not have caused a problem.
Toxicology testing measured .58 micrograms of cocaine per milliliter of blood drawn from a vein in her leg during the autopsy, which Pinsky called a moderate level.
Her cocaine use appeared to have occurred "in the time period just immediately prior to her collapse in the bathtub at the hotel," Chief Coroner Craig Harvey told reporters when he released the preliminary report last month.
Investigators found "a small spoon with a white crystal like substance in it and a rolled up piece of white paper" in the bathroom where Houston drowned, coroner's investigator Kristy McCracken wrote.
"Remnants of a white powdery substance" were found on a bathroom counter, McCracken wrote.
"I also collected remnants of a white powdery substance from out of a drawer and from the bottom of a mirror in the same drawer in the bathroom counter," she wrote.
Detectives found a "plethora of medications bottles" in the hotel room, although the coroner concluded the prescription drugs "did not contribute to the death."
Along with cocaine, the toxicology tests found other drugs in her body, including marijuana, the anti-anxiety drug Xanax, the muscle relaxant Flexeril and the allergy medicine Benadryl, the report said.
Houston was last seen alive by her personal assistant in her Beverly Hilton hotel room at about 3 p.m. that Saturday, the report said. The assistant left to run errands after telling Houston to take a bath in preparation for a pre-Grammy Awards party at the hotel that night, it said.
When the assistant returned to the locked room at 3:35 p.m.. she found Houston "lying face down in the bathtub filled with water, unresponsive."
"The assistant called for her bodyguard, and together they pulled the decedent out of the bathtub," the report said.
When paramedics arrived about 10 minutes later they moved Houston to the living room floor. It was at 3:55 p.m., 20 minutes after she was found by the assistant, that paramedics concluded she was dead, the report said.
Houston won six Grammys and sold 170 million albums, singles and videos over her career.
In recent years, the singer's accomplishments were overtaken by her struggles with drug addiction.
CNN's Jack Hannah and Kareen Wynter contributed to this report.